Nowadays, LCD (liquid crystal display) TV, PC, Monitors, display devices are widely used. In the manufacturing of LCD modules, particulate matter (PM) has great adverse effect on the quality of LCD modules. For example, in the manufacturing process of thin film transistor (TFT), the exposure machine may be near to the surface of the glass substrate (the distance there-between is about 200 micron), especially when the area of the mask is large. In such situation, if the particulate matter on the surface of the glass substrate adheres to the mask, the mask may be damaged.